Efficient way to modify an object from array of objects via index and insert new objects in the same array in mongodb? - mongodb

Question

I have an array available in the db with the key heros.
Heros: [
{
name: 'Ironman',
country: 'USA'
},
{
name: 'Shaktiman',
country: 'India'
},
{
name: 'Black Panther',
country: 'Wakanda'
}
]
and I have a new array which basically have additional heros:
additionalHeros = [{ name: 'Wonder woman', country: 'USA' }, { name: 'Kenshiro', country: 'Japan' }]
I want to update the name and country of a hero at a specific index say 1 and replace it with new values. After that I have to put all the additional heros in the same query.
After executing update query, expected result would be:
At index 2 -> update name: 'Krishh', country: 'India' -> put rest of the heros
Updated db value for heros is:
Heros: [
{
name: 'Ironman',
country: 'USA'
},
{
name: 'Shaktiman',
country: 'India'
},
{
name: 'Krishh',
country: 'India'
},
{ name: 'Wonder woman',
country: 'USA'
},
{ name: 'Kenshiro',
country: 'Japan'
}
]
I'm aware of the part to push a value but I can't find any efficient way to update and insert at once
$push: { heros: { $each: additionalHeros } }

Answer 1

The regular update query will not allow to do 2 operations in the same field, it will create a conflict error
You can use update with aggregation pipeline starting from MongoDB 4.2, but i think this approach is not efficient and you want an efficient approach,
$map to iterate loop of heros array
$indexOfArray to get the index of the current object in heros array
$cond to check if the above return index match with our input index then update the latest value otherwise return the same object
second $set stage to add new heros using $concatArrays operator
additionalHeros = [{ name: 'Wonder woman', country: 'USA' }, { name: 'Kenshiro', country: 'Japan' }]
updateIndex = {
name: "Krishh",
country: "India"
}
index = 1
db.collection.updateOne(
{}, // your query
[{
$set: {
heros: {
$map: {
input: "$heros",
in: {
$cond: [
{
$eq: [
{
$indexOfArray: [
"$heros",
{
name: "$$this.name",
country: "$$this.country"
}
]
},
index
]
},
updateIndex,
"$$this"
]
}
}
}
}
},
{
$set: {
heros: {
$concatArrays: ["$heros", additionalHeros]
}
}
}]
)
Playground
You can do two separate update queries or bulkWrite query
update specific index property
db.collection.updateOne(
{}, // your query
{
$set: {
"heros.1.name": "Krishh",
"heros.1.country": "India"
}
}
)
Playground
push array in heros
db.collection.updateOne(
{}, // your query
{
$push: {
heros: {
$each: [
{
name: "Wonder woman",
country: "USA"
},
{
name: "Kenshiro",
country: "Japan"
}
]
}
}
}
)
Playground

Answer 2

this will work
let document be
{
"_id" : "heroes",
"Heros" : [
{
"name" : "Ironman",
"country" : "USA"
},
{
"name" : "Shaktiman",
"country" : "India"
},
{
"name" : "Black Panther",
"country" : "Wakanda"
}
]
}
Code would be
let additionalHeros = [{ name: 'Wonder woman', country: 'USA' }, { name: 'Kenshiro', country: 'Japan' }]
let index = 2;
let data = { name: 'Krishh', country: 'India' }
let updateQuery = {};
updateQuery[`Heros.${index}`] = data;
let ops = [];
ops.push(
{
updateOne: {
filter: { _id: "heroes" },
update: {
$set: updateQuery,
},
upsert: true
}
},
);
ops.push(
{
updateOne: {
filter: { _id: "heroes" },
update: {
$push: { Heros: { $each: additionalHeros } }
},
upsert: true
}
},
);
let x = await db1.bulkWrite(ops, { ordered: true, upsert: true })
Then Output would be
{
"_id" : "heroes",
"Heros" : [
{
"name" : "Ironman",
"country" : "USA"
},
{
"name" : "Shaktiman",
"country" : "India"
},
{
"name" : "Krishh",
"country" : "India"
},
{
"name" : "Wonder woman",
"country" : "USA"
},
{
"name" : "Kenshiro",
"country" : "Japan"
}
]
}